1. Field of the Invention
The present invention relates to a switching mechanism usable underwater, and more particularly to a switching mechanism usable underwater for use in a device capable of being not only used on land but also used underwater.
2. Description of the Related Art
Devices used underwater, for example, such as underwater cameras or the like are provided with various kinds of operating switches that can be operated underwater. In contrast to operating switches that are only used on land, such an operating switch used underwater is required to be designed not only to have water-tightness but also to have water-tightness withstanding up to a predetermined water pressure. In general, when the operating switch used underwater is designed, to what extent of a water depth the operating switch can withstand, is decided in consideration of a usage pattern, size, weight, and a price of the device. The deeper the designed depth of water, the larger the water pressure applied to the device. However, because hydrostatic pressure is uniformly applied to an entire surface of the device, the hydrostatic pressure is applied not only to an exterior package of the device but also to the operating switch, as it is obvious.
In a case when the operating switch is that of a pressure-type, it is possible that the operating switch is turned on/off by pressing force caused by the water pressure. Therefore, the pressure-type switch is configured to generate biasing force that can withstand the water pressure by, for example, providing a spring or the like inside thereof. In this case, the deeper the water depth designed for the device, the stronger the biasing force necessary for the device. Therefore, when such a device is used on land or underwater in relatively shallow water, large pressing force is required to operate the operating switch. In addition, because the required pressing force to operate such an operating switch varies corresponding to the water depth, operability of the operating switch is not good.
As an art that can improve these shortcomings, for example, in Japanese Unexamined Utility Model Registration Application Publication No. 51-111343, a shutter release of a waterproof camera, in which a balancing pressure receiving face having approximately the same area as that of a pressure receiving face of a pressing portion is provided in a shutter release member so as to balance water pressure applied to both the pressure receiving faces, is described. More concretely, the pressure receiving face of the pressing portion is disposed at an upper face side of the waterproof camera and the balancing pressure receiving face is disposed at a lower face side thereof, respectively and the shutter release member is formed into a longitudinal shape that connects the upper face and the lower face of the waterproof camera. In addition, the shutter release member is configured to be movable in a vertical direction connecting the upper face and the lower face of the waterproof camera. According to such a configuration, the shutter release member is prevented from being improperly pressed by the water pressure regardless of the water depth.